[PATCH v4 net 2/2] selftests: net: simple selftest for ipvtap

[PATCH v4 net 2/2] selftests: net: simple selftest for ipvtap

[Dmitry Skorodumov]

This is a simple ipvtap test to test handling
IP-address add/remove on ipvlan interface.

It creates a veth-interface and then creates several
network-namespace with ipvlan0 interface in it linked to veth.

Then it starts to add/remove addresses on ipvlan0 interfaces
in several threads.

At finish, it checks that there is no duplicated addresses.

Signed-off-by: Dmitry Skorodumov <skorodumov.dmitry@huawei.com>
---
v4:
  - Removed unneeded modprobe
  - Number of threads is 8, if KSFT_MACHINE_SLOW==yes.
    It is needed, since on debug-build test may take more than 15 minutes.
  - Now veth is created in own namespace
  - Added comment about why test adds/removes random ip

 tools/testing/selftests/net/Makefile       |   1 +
 tools/testing/selftests/net/config         |   2 +
 tools/testing/selftests/net/ipvtap_test.sh | 166 +++++++++++++++++++++
 3 files changed, 169 insertions(+)
 create mode 100755 tools/testing/selftests/net/ipvtap_test.sh

diff --git a/tools/testing/selftests/net/Makefile b/tools/testing/selftests/net/Makefile
index b66ba04f19d9..45c4ea381bc3 100644
--- a/tools/testing/selftests/net/Makefile
+++ b/tools/testing/selftests/net/Makefile
@@ -48,6 +48,7 @@ TEST_PROGS := \
 	ipv6_flowlabel.sh \
 	ipv6_force_forwarding.sh \
 	ipv6_route_update_soft_lockup.sh \
+	ipvtap_test.sh \
 	l2_tos_ttl_inherit.sh \
 	l2tp.sh \
 	link_netns.py \
diff --git a/tools/testing/selftests/net/config b/tools/testing/selftests/net/config
index 1e1f253118f5..5702ab8fa5ad 100644
--- a/tools/testing/selftests/net/config
+++ b/tools/testing/selftests/net/config
@@ -48,6 +48,7 @@ CONFIG_IPV6_SEG6_LWTUNNEL=y
 CONFIG_IPV6_SIT=y
 CONFIG_IPV6_VTI=y
 CONFIG_IPVLAN=m
+CONFIG_IPVTAP=m
 CONFIG_KALLSYMS=y
 CONFIG_L2TP=m
 CONFIG_L2TP_ETH=m
@@ -122,6 +123,7 @@ CONFIG_TEST_BPF=m
 CONFIG_TLS=m
 CONFIG_TRACEPOINTS=y
 CONFIG_TUN=y
+CONFIG_TAP=m
 CONFIG_USER_NS=y
 CONFIG_VETH=y
 CONFIG_VLAN_8021Q=y
diff --git a/tools/testing/selftests/net/ipvtap_test.sh b/tools/testing/selftests/net/ipvtap_test.sh
new file mode 100755
index 000000000000..b4e18fc7ada0
--- /dev/null
+++ b/tools/testing/selftests/net/ipvtap_test.sh
@@ -0,0 +1,167 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+#
+# Simple tests for ipvtap
+
+
+#
+# The testing environment looks this way:
+#
+# |------HNS-------|     |------PHY-------|
+# |      veth<----------------->veth      |
+# |------|--|------|     |----------------|
+#        |  |
+#        |  |            |-----TST0-------|
+#        |  |------------|----ipvlan      |
+#        |               |----------------|
+#        |
+#        |               |-----TST1-------|
+#        |---------------|----ipvlan      |
+#                        |----------------|
+#
+
+ALL_TESTS="
+	test_ip_set
+"
+
+source lib.sh
+
+DEBUG=0
+
+VETH_HOST=vethtst.h
+VETH_PHY=vethtst.p
+
+NS_COUNT=32
+IP_ITERATIONS=1024
+[ "$KSFT_MACHINE_SLOW" = "yes" ] && NS_COUNT=8
+
+ns_run() {
+	ns=$1
+	shift
+	if [[ "$ns" == "global" ]]; then
+		"$@" >/dev/null
+	else
+		ip netns exec "$ns" "$@" >/dev/null
+	fi
+}
+
+test_ip_setup_env() {
+	setup_ns NS_PHY
+	setup_ns HST_NS
+
+	# setup simulated other-host (phy) and host itself
+	ns_run "$HST_NS" ip link add $VETH_HOST type veth peer name $VETH_PHY \
+		netns "$NS_PHY" >/dev/null
+	ns_run "$HST_NS" ip link set $VETH_HOST up
+	ns_run "$NS_PHY" ip link set $VETH_PHY up
+
+	for ((i=0; i<NS_COUNT; i++)); do
+		setup_ns ipvlan_ns_$i
+		ns="ipvlan_ns_$i"
+		if [ "$DEBUG" = "1" ]; then
+			echo "created NS ${!ns}"
+		fi
+		if ! ns_run "$HST_NS" ip link add netns ${!ns} ipvlan0 \
+		    link $VETH_HOST \
+		    type ipvtap mode l2 bridge; then
+			exit_error "FAIL: Failed to configure ipvlan link."
+		fi
+	done
+}
+
+test_ip_cleanup_env() {
+	ns_run "$HST_NS" ip link del $VETH_HOST
+	cleanup_all_ns
+}
+
+exit_error() {
+	echo "$1"
+	exit $ksft_fail
+}
+
+rnd() {
+	echo $(( RANDOM % 32 + 16 ))
+}
+
+test_ip_set_thread() {
+	# Here we are trying to create some IP conflicts between namespaces.
+	# If just add/remove IP, nothing interesting will happen.
+	# But if add random IP and then remove random IP,
+	# eventually conflicts start to apear.
+	ip link set ipvlan0 up
+	for ((i=0; i<IP_ITERATIONS; i++)); do
+		v=$(rnd)
+		ip a a "172.25.0.$v/24" dev ipvlan0 2>/dev/null
+		ip a a "fc00::$v/64" dev ipvlan0 2>/dev/null
+		v=$(rnd)
+		ip a d "172.25.0.$v/24" dev ipvlan0 2>/dev/null
+		ip a d "fc00::$v/64" dev ipvlan0 2>/dev/null
+	done
+}
+
+test_ip_set() {
+	RET=0
+
+	trap test_ip_cleanup_env EXIT
+
+	test_ip_setup_env
+
+	declare -A ns_pids
+	for ((i=0; i<NS_COUNT; i++)); do
+		ns="ipvlan_ns_$i"
+		ns_run ${!ns} bash -c "$0 test_ip_set_thread"&
+		ns_pids[$i]=$!
+	done
+
+	for ((i=0; i<NS_COUNT; i++)); do
+		wait "${ns_pids[$i]}"
+	done
+
+	declare -A all_ips
+	for ((i=0; i<NS_COUNT; i++)); do
+		ns="ipvlan_ns_$i"
+		ip_output=$(ip netns exec ${!ns} ip a l dev ipvlan0 | grep inet)
+		while IFS= read -r nsip_out; do
+			if [[ -z $nsip_out ]]; then
+				continue;
+			fi
+			nsip=$(awk '{print $2}' <<< "$nsip_out")
+			if [[ -v all_ips[$nsip] ]]; then
+				RET=$ksft_fail
+				log_test "conflict for $nsip"
+				return "$RET"
+			else
+				all_ips[$nsip]=$i
+			fi
+		done <<< "$ip_output"
+	done
+
+	if [ "$DEBUG" = "1" ]; then
+		for key in "${!all_ips[@]}"; do
+			echo "$key: ${all_ips[$key]}"
+		done
+	fi
+
+	trap - EXIT
+	test_ip_cleanup_env
+
+	log_test "test multithreaded ip set"
+}
+
+if [[ "$1" == "-d" ]]; then
+	DEBUG=1
+	shift
+fi
+
+if [[ "$1" == "-t" ]]; then
+	shift
+	TESTS="$*"
+fi
+
+if [[ "$1" == "test_ip_set_thread" ]]; then
+	test_ip_set_thread
+else
+	require_command ip
+
+	tests_run
+fi
-- 
2.43.0

Re: [PATCH v4 net 2/2] selftests: net: simple selftest for ipvtap

[Jakub Kicinski]

On Tue, 30 Dec 2025 17:03:24 +0300 Dmitry Skorodumov wrote:
> @@ -122,6 +123,7 @@ CONFIG_TEST_BPF=m
>  CONFIG_TLS=m
>  CONFIG_TRACEPOINTS=y
>  CONFIG_TUN=y
> +CONFIG_TAP=m

alphabetical order please

>  CONFIG_USER_NS=y
>  CONFIG_VETH=y
>  CONFIG_VLAN_8021Q=y
> diff --git a/tools/testing/selftests/net/ipvtap_test.sh b/tools/testing/selftests/net/ipvtap_test.sh
> new file mode 100755

> +NS_COUNT=32
> +IP_ITERATIONS=1024
> +[ "$KSFT_MACHINE_SLOW" = "yes" ] && NS_COUNT=8

This still fails on our slow VMs with debug kernel enabled (even tho
they set KSFT_MACHINE_SLOW). The test runs for 15+ minutes without
printing anything. That's pretty bad, humans running this tests will
also have no idea what's going on. Maybe limit the runtime of the test
as well as the iterations? To 1min? It takes <50sec on non-debug kernels
in our CI.
-- 
pw-bot: cr